This invention relates to sensing devices incorporating single crystal semiconductor wafers and more particularly to a reduced blooming vidicon having an improved anti-reflection coating for increased quantum efficiency of the device.
Sensing devices such as silicon vidicons and silicon intensifier tubes employ sensing elements or targets comprising single crystal semiconductor wafers. The operation of such sensing elements in these devices is well known in the art. Recently, improvements have been made in reducing and stabilizing the blooming effects of these targets as described in pending patent application Ser. No. 838,713, filed Oct. 3, 1977 by Savoye et al., entitled "Reduced Blooming Devices." Although the blooming characteristics of these devices have been improved, the quantum efficiency is unaffected. As described in the aforementioned application, the reduced blooming characteristics of the target are stabilized by depositing a passivating layer of boron containing silica glass onto the input signal sensing surface of the silicon target. Prior to the recent advances in reduced blooming targets, the silicon targets had been coated with an anti-reflecting coating of silicon monoxide, which is well known in the art. Using this silicon monoxide coating, it was typical to achieve quantum efficiencies approaching 96-97% at certain wavelengths of incident light. However, deposition of the silicon monoxide anti-reflecting layer on the passivating layer of the reduced blooming targets produces little, if any, improvement in the quantum efficiency of the reduced blooming device. It is thus desirable to achieve a sensing device that has reduced and stabilized blooming characteristics and improved quantum efficiency.